1. Field of the Invention
The present invention relates, in general, to electronic thermometers and, more particularly, pertains to an assembly for an electronic thermometer which provides a highly accurate and conveniently employable instrument.
2. Discussion of the Prior Art
Electronic thermometers typically utilize a thermoelectric element, such as a thermistor, to sense a patient's temperature. An electronic signal processor is adapted to receive an electrical signal from the thermistor and to provide an accurate temperature measurement within a relatively short period of time. These thermometer units generally provide a digital display of the measured temperature through the intermediary of nixie tubes, light emitting diodes, liquid crystals, and the like. Electronic thermometers of this type are disclosed, for example, in U.S. Pat. No. 3,978,325 for Electronic Temperature Computer, and U.S. patent application Ser. No. 599,971 for Electronic Thermometer, filed July 29, 1975.
Electronic thermometers of this nature frequently constitute replacements for conventional glass-bulb mercury thermometers, particularly in applications wherein large numbers of temperature measurements are continually or frequently taken, particularly in facilities such as hospitals and clinics.
Since these thermometer units, in general, are intended for use with an extensive number of patients, the instrument must be designed so as to be easily sterilizable after each measurement. One approach to providing an uncontaminated temperature probe for each patient is to utilize a disposable sheath or cover for the thermometer probe and sensor. Thus, an electronic thermometer incorporating disposable probe sheaths should provide for their convenient and rapid mounting and subsequent replacement on the thermometer. Moreover, the instrument should allow used probe sheaths to be conveniently disposed of without necessitating any direct contact between the hands of the personnel using the instrument and the sheaths. Further, the thermometer probe sheath and probe should be of a design whereby each replacement sheath or cover will be accurately and precisely positioned on the instrument with the thermistor bead of the electronic instrument being in intimate physical contact with the interior of the sheath in order to afford an optimum degree of heat transfer from the patient to the thermistor bead.
Mead U.S. Pat. No. 3,678,751 for a Thermometer Cover discloses an electronic thermometer design typical of many in the prior art. The thermometer has a thermistor element for sensing a patient's temperature mounted at the end of a hollow cylindrical stainless steel shaft. A probe sheath is placed over the shaft, and is adapted to be disposed of after the taking of each measurement. The thermometer disclosed by this patent uses a rigid, as opposed to a flexible, shaft, and also the manner in which the probe sheaths are dislodged from the instrument is quite different from the approach taken by the present invention.
Mueller et al U.S. Pat. Nos. 3,729,998 and 3,832,699 disclose a rather complex instrument in which a temperature sensitive thermistor is mounted at the end of a rigid plastic shaft. A disposable probe sheath is placed over the shaft and extends onto several longitudinally oriented ribs formed on the instrument. An axially displaceable housing member facilitates removal of a used sheath. Although the disclosed design specifically provides for the removal of a used sheath, the instrument does not incorporate a flexible shaft to assist in this function. Further, the sheath retainer element is quite different in structure from that employed in the present invention.
Sato U.S. Pat. No. 3,738,172 for Temperature Sensing Probe and Disposable Probe Cover discloses an electronic thermometer having two relatively movable handle sections which are spring biased together. The two handle sections are separated slightly when a disposable probe sheath is placed over the shaft of the instrument. The probe sheath is held securely in place on the instrument by a split ring mounted around the instrument's shaft. A used sheath is disposed of by pressing together the two relatively movable handle sections, which dislodges the sheath from the split ring. This instrument differs from the present invention in several material aspects. Sato uses a nonflexible shaft, and the manner in which a disposable sheath is mounted thereon is quite different from that of the present invention. Also, the two relatively movable handle sections of this patent are spring biased together to provide a manner of usage of the instrument which is somewhat different from that of the present invention.